Fingerprint sensor

ABSTRACT

A fingerprint sensor is provided and includes substrate; sensor electrodes arranged on substrate; first switches coupled to sensor electrodes; organic layer covering sensor electrodes; control line drive circuit in a first direction; signal line drive circuit in a second direction orthogonal to the first direction; signal lines coupled to the first switches; control lines coupling first switches to control line drive circuit; sensor drive electrode surrounding sensor electrodes; second switches between signal line drive circuit and signal lines; first number of third switches between signal line drive circuit and first number of second switches, wherein surface of organic layer is lower than sensor drive electrode, and wherein first number is less than number of all second switches.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of U.S. patentapplication Ser. No. 17/187,101, filed on Feb. 26, 2021, whichapplication is a continuation of U.S. patent application Ser. No.16/845,911, filed on Apr. 10, 2020, issued as U.S. Pat. No. 10,963,663on Mar. 30, 2021, which application is a continuation of U.S. patentapplication Ser. No. 16/531,887, filed on Aug. 5, 2019, issued as U.S.Pat. No. 10,621,405 on Apr. 14, 2020, which application is acontinuation of U.S. patent application Ser. No. 15/469,755, filed onMar. 27, 2017, issued as U.S. Pat. No. 10,372,961 on Aug. 6, 2019, whichapplication claims priority from Japanese Application No. 2016-069293,filed on Mar. 30, 2016, and Japanese Application No. 2017-053516, filedon Mar. 17, 2017, the contents of which are incorporated by referenceherein in its entirety.

BACKGROUND 1. Technical Field

The present invention relates to a fingerprint sensor, a fingerprintsensor module, and a method for manufacturing the fingerprint sensor.

2. Description of the Related Art

Recent years have seen development of, for example, high-resolutioncapacitance detection devices that can detect a microstructure, such asunevenness of a surface of a finger, as a way of biometricauthentication.

Of such devices, however, conventional fingerprint sensors are formed ona single-crystal silicon substrate, and hence are easily broken whenpressed by a finger, which is a problem.

Japanese Patent Application Laid-open Publication No. 2004-317353describes improvement in durability of a fingerprint sensor formed on aninsulating substrate.

However, fingerprint sensors such as those described above have beenrequired to be further improved in durability. The fingerprint sensorshave also been required to have both high durability and high detectionsensitivity.

For the foregoing reasons, there is a need for a fingerprint sensor withexcellent durability, a module for the fingerprint sensor, and a methodfor manufacturing the fingerprint sensor. Furthermore, there is a needfor a fingerprint sensor that achieves not only excellent durability butalso excellent detection sensitivity, a module for the fingerprintsensor, and a method for manufacturing the fingerprint sensor.

SUMMARY

According to an aspect, a fingerprint sensor includes a first glasssubstrate, a second glass substrate, and a plurality of sensorelectrodes between the first glass substrate and the second glasssubstrate. The first glass substrate and the second glass substrate arebonded together by a sealing material with the plurality of sensorelectrodes interposed therebetween.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view of a fingerprint sensor according to an embodimentof the present invention;

FIG. 2 is a side view of the fingerprint sensor according to theembodiment;

FIG. 3 is a sectional view of the fingerprint sensor according to theembodiment;

FIG. 4 is a partially enlarged view of the sectional view of thefingerprint sensor according to the embodiment;

FIG. 5 is a sectional view illustrating an exemplary bonded structure ofthe fingerprint sensor according to the embodiment;

FIG. 6 is a sectional view illustrating another exemplary bondedstructure of the fingerprint sensor according to the embodiment;

FIG. 7 is a sectional view illustrating still another exemplary bondedstructure of the fingerprint sensor according to the embodiment;

FIG. 8 is a circuit diagram illustrating an example of a detectionprinciple of the fingerprint sensor according to the embodiment;

FIG. 9 is a sectional view of a second counter electrode according tothe embodiment;

FIG. 10 is a sectional view of another example of the second counterelectrode according to the embodiment;

FIG. 11 is a plan view of the second counter electrode according to theembodiment;

FIG. 12 is a sectional view of a sensor drive electrode according to theembodiment;

FIG. 13 is a sectional view of another example of the sensor driveelectrode according to the embodiment;

FIG. 14 is a plan view of the sensor drive electrode according to theembodiment;

FIG. 15 is a diagram illustrating an example of a detection principle ofthe sensor drive electrode according to the embodiment;

FIG. 16 is a schematic diagram illustrating a method for driving thefingerprint sensor according to the embodiment;

FIG. 17 is a schematic diagram and a timing diagram illustrating amethod for driving the second counter electrode according to theembodiment;

FIG. 18 is a schematic diagram and a timing diagram illustrating amethod for driving the sensor drive electrode according to theembodiment;

FIG. 19 is an exemplary plan view of a fingerprint sensor moduleaccording to the embodiment;

FIG. 20 is an exemplary side view of the fingerprint sensor moduleaccording to the embodiment;

FIG. 21 is a sectional view of a decorative layer according to theembodiment;

FIG. 22 is another exemplary sectional view of the decorative layeraccording to the embodiment; and

FIG. 23 is an exemplary plan view of a dummy electrode according to theembodiment.

DETAILED DESCRIPTION

The following describes an embodiment for carrying out the presentinvention. The present invention is not limited to the description ofthe embodiment to be given below. Components to be described belowinclude those easily conceivable by those skilled in the art, and thosesubstantially the same. The components to be described below can becombined as appropriate. The present disclosure is merely an example,and includes those that can be appropriately modified or easilyconceivable by those skilled in the art. To further clarify thedescription, widths, thicknesses, shapes, and the like of various partsmay be schematically illustrated in the drawings as compared with actualaspects thereof. However, they are merely examples, and interpretationof the invention is not limited thereto. The same element as thatillustrated in a drawing that has already been discussed is denoted bythe same reference numeral through the description and the drawings, anddetailed description thereof will not be repeated in some cases whereappropriate.

1-1. Overall Configuration

FIG. 1 is a plan view illustrating a configuration example of afingerprint sensor according to the present embodiment.

The fingerprint sensor 1 includes a first glass substrate SUB1, a secondglass substrate SUB2, sensor electrodes SE, control lines C1, signallines S1, a control line drive circuit CD, a signal line drive circuitMU, a detection region AA, and a frame region PA. The sensor electrodesSE are formed above the first glass substrate SUB1, above which thesecond glass substrate SUB2 is stacked. That is, the fingerprint sensor1 has a structure in which the sensor electrodes SE are interposedbetween the two glass substrates.

The first and the second glass substrates SUB1 and SUB2 are bondedtogether with a sealing material (not illustrated).

The fingerprint sensor 1 includes the sensor electrodes SE arrangedthereon, and is provided with the detection region AA for detecting afingerprint or the like, and with the frame region PA outside thedetection region AA. The sensor electrodes SE for the fingerprintdetection are interposed between the two glass substrates, and the glasssubstrates are bonded together, so that the sensor electrodes SE can bephysically and chemically protected and prevented from deformation andbreakage when pressed from above. Such a fingerprint sensor is moredurable than fingerprint sensors protected by, for example, a resinfilm.

When the sensor electrodes SE are protected by being interposed betweenmembers such as an insulating substrate and a resin film having a largedifference in linear expansion coefficient, the fingerprint sensor iswarped due to the difference in the linear expansion coefficient underhigh temperature conditions or low temperature conditions. However,bonding the two glass substrates with the sensor electrodes SEinterposed therebetween can prevent the warp of the sensor.

It is preferable that the first and the second glass substrates SUB1 andSUB2 are formed of the same material having an equal linear expansioncoefficient, so that the warp of the sensor can be further prevented.

Employing the structure of interposing the sensor electrodes SE betweenthe two glass substrates allows the glass substrates to be controlled inthickness, for example, using a wet etching method. As a result, theglass of the fingerprint sensor is easily reduced in thickness. That is,bonding the two glass substrates with the sensor electrodes SEinterposed therebetween can simultaneously achieve a reduction inthickness of the fingerprint sensor and prevention of the warp of thefingerprint sensor. If a glass substrate disposed between the sensorelectrodes SE and a finger is too thick, the detection sensitivity ofthe fingerprint sensor drops. However, the present embodiment canprovide the fingerprint sensor 1 having excellent detection sensitivity.If the glass substrate disposed between the sensor electrodes SE and thefinger is too thin, the durability of the fingerprint sensor drops insome cases. However, the present embodiment enables easy control of thefilm thickness of the glass substrate, and thus can provide thefingerprint sensor 1 having desired durability. The shapes of the glasssubstrates SUB1 and SUB2 and the shapes of the detection region AA andthe frame region PA are not limited to the illustrated shapes thereof,and may be square, rectangular, circular, or polygonal.

The sensor electrodes SE are arrayed in the detection region AA of thefirst glass substrate SUB1, and the signal line drive circuit MU and thecontrol line drive circuit CD are disposed in the frame region PA. Thesensor electrodes SE are formed in a matrix so as to have a plurality ofpatterns arrayed in the X-direction and the Y-direction at least in thedetection region AA. Each adjacent pair of the sensor electrodes SE isdivided by a slit. To detect a microstructure, such as a fingerprint,the sensor electrodes SE arranged in the detection region AA arepreferably arranged at a density of 250 to 1000 pixels per inch (PPI)when converted such that each of the sensor electrodes SE corresponds toa pixel. This arrangement allows the sensor electrodes SE to have aresolution corresponding to a pixel resolution in a range of 250 to 1000PPI.

The signal line drive circuit MU supplies drive signals for thefingerprint detection to the sensor electrodes SE through the signallines S1, or outputs a detection signal for the fingerprint detection.The signal lines S1 extend in the Y-direction and are arrayed in theX-direction at least in the detection region AA. Each of the signallines S1 is disposed so as to correspond to the respective sensorelectrodes SE in at least one column extending in the Y-direction. Thesignal line drive circuit MU selects the signal line S1 for the driveand detection according to a predetermined selection signal. The signalline drive circuit MU includes a selection circuit such as a multiplexercircuit.

The control line drive circuit CD supplies a selection signal througheach of the control lines C1 to select sensor electrodes SE to bedriven. The control lines C1 extend in the X-direction and are arrayedin the Y-direction at least in the detection region AA. Each of thecontrol lines C is disposed so as to correspond to the respective sensorelectrodes SE in at least one predetermined row of the sensor electrodesSE extending in the X-direction. The control line drive circuit CDincludes a transfer circuit such as a shift register circuit, and aselection circuit such as a decoder circuit.

FIG. 2 is a side view illustrating a configuration of the fingerprintsensor according to the present embodiment. As illustrated in FIG. 2 ,when a finger F above the second glass substrate SUB2 is in proximitythereto or in contact therewith, a sensor electrode (not illustrated)formed on the first glass substrate SUB1 detects the fingerprint of thefinger.

In the present embodiment, the main surface of the second glasssubstrate SUB2 has a smaller area than that of the first glass substrateSUB1. A step D is formed near an end T of the second glass substrateSUB2. For example, signal wiring, a flexible substrate, and a terminal(connector) can be disposed in a region of the first substrate where thesecond substrate does not overlap the first substrate thereabove.

The fingerprint sensor of the present embodiment can be easily reducedin size, thickness, and weight, and can have excellent durability andhigh detection sensitivity. The fingerprint sensor of the presentembodiment can be built into a credit card or the like to provide a cardwith a fingerprint authentication function. That is, the fingerprintsensor of the present embodiment can be used as a thin sensor or acompact sensor with high resolution.

At least one of the first glass substrate SUB1 and the second glasssubstrate SUB2 of the fingerprint sensor according to the presentembodiment preferably has a thickness in the range of 100 μm to 300 μm.If the thickness is smaller than 100 μm, the durability of thefingerprint sensor drops in some cases. If the thickness exceeds 300 μm,the sensitivity of the fingerprint sensor drops in some cases. Everyside of the first and the second glass substrates SUB1 and SUB2 of thefingerprint sensor according to the present embodiment preferably has alength in the range of 5 mm to 30 mm. If one side of the glasssubstrates is 5 mm or smaller in length, the resolution of thefingerprint detection is insufficient in some cases. If one side of theglass substrates exceeds 30 mm in length, the fingerprint sensorincreases in size in some cases.

1-2. Configuration Example of Fingerprint Sensor

FIG. 3 is an exemplary schematic sectional view of the fingerprintsensor 1 according to the embodiment.

A sensor circuit 3 is formed on the first glass substrate SUB1. Thesensor circuit 3 includes wiring (not illustrated), such as controllines and signal lines, and switch elements that supply the drivesignals from the signal lines to the sensor electrodes SE according tocontrol signals supplied from the control lines. A planarizing film PLNis formed on the sensor circuit 3. The planarizing film PLN is formed ofan organic material such as an acrylic resin. Using an organic materialallows the planarizing film PLN to have a larger film thickness. Thiscan reduce parasitic capacitances between the sensor electrodes SE andthe sensor circuit 3 and between a first counter electrode CE1 and thesensor circuit 3, and thus enables improvement in the detection speedand the detection sensitivity of the sensor, and reduction in electricpower consumption.

The first counter electrode CE1 facing the sensor electrodes SE isformed on the planarizing film PLN. The first counter electrode CE1 hasa function as, for example, a guard electrode. In a high-resolutioninput detection device, such as the fingerprint sensor, that recognizesa microstructure, a larger number of the small sensor electrodes SE aredensely arranged in the detection region, thereby necessitating a drivecircuit, a selection circuit, and control wiring for sequentiallydriving the sensor electrodes SE. Therefore, the guard electrode isdisposed between the sensor circuit including such circuits and wiringand the sensor electrodes SE so that noise and the parasiticcapacitances can be reduced. The first counter electrode CE1 is formedof a conductive layer of, for example, indium tin oxide (ITO), and isformed into, for example, a solid pattern shape covering at least theentire surface in the detection region AA in which the sensor electrodesSE are arranged. The first counter electrode CE1 may, however, have ashape divided into a plurality patterns. The first counter electrode CE1may be formed of ITO, a light-transmitting conductive material, such asindium zinc oxide (IZO) and zinc oxide (ZnO), or a light-blockingconductive material, such as a metal. It is preferable that the firstcounter electrode CE1 faces the sensor electrodes SE so as to cover theentire detection region AA, because the guard effect is improved.

The first counter electrode CE1 may be set to a floating potential, ormay be supplied with a predetermined potential. While an active guardpotential supplied to the first counter electrode CE1 is not limited, ahigher effect of reducing the parasitic capacitances between the sensorelectrodes SE and the sensor circuit 3 is preferably obtained bysupplying a signal having the same phase as that of the drive signalsupplied to each of the sensor electrodes SE to the first counterelectrode CE1 at the same timing as the timing of supplying the drivesignal to the sensor electrodes SE. The guard signal synchronized withthe drive signal of the sensors in this manner is at the active guardpotential. The voltage of the signal at the active guard potential onlyneeds to have the same phase as that of the drive signal of the sensors.It is more preferable to use the active guard potential having the samewaveform with the same phase and the same amplitude as those of thedrive signal.

An insulating film 2 is formed on the first counter electrode CE1, andthe sensor electrodes SE are formed on the insulating film 2. The sensorelectrodes SE are formed of, for example, ITO. The sensor electrodes SEmay be formed of IZO, ZnO, or metal films. An alignment film AL1 isformed on the sensor electrodes SE.

An overcoat layer (protection layer) OC is formed on the second glasssubstrate SUB2. A spacer SP is formed on the overcoat layer OC. Analignment film AL2 is formed on the spacer SP. A liquid crystal layer LQis disposed between the alignment film AL1 and the alignment film AL2.That is, a gap formed between the first and the second glass substratesSUB1 and SUB2 is filled with liquid crystals of the liquid crystal layerLQ. The first and the second glass substrates SUB1 and SUB2 are bondedtogether in the frame region PA, so that a vacuum layer or an air layeris included between the glass substrates unless the liquid crystals areinjected in the gap between the glass substrates. If the vacuum layer orthe air layer is interposed between the sensor electrodes SE and thesubstrate (second glass substrate SUB2 in the present embodiment)touched by the finger, the detection sensitivity of the fingerprintsensor drops in some cases. Therefore, the vacuum layer or the air layeris preferably filled with a filler material, such as the liquidcrystals. As will be described later, the gap between the first and thesecond glass substrates SUB1 and SUB2 may be filled with the sealingmaterial.

To prevent the liquid crystals injected between the first and the secondglass substrates SUB1 and SUB2 from leaking out, and to prevent air fromentering the gap between the first and the second glass substrates SUB1and SUB2 from the outside, the first and the second glass substratesSUB1 and SUB2 are preferably bonded together without a gap, i.e., sealedby the sealing material.

FIG. 4 is an exemplary enlarged view of the sensor circuit formed on thefirst glass substrate SUB1. FIG. 4 is an enlarged schematic diagram of asectional view of the fingerprint sensor of FIG. 1 taken along the linein the X-direction. As illustrated in FIG. 4 , each of the control linesC1 and a sub-guard electrode SGE are formed on the first glass substrateSUB1. The control line C1 and the sub-guard electrode SGE may bedirectly formed on the first glass substrate SUB1, or may be formed withan insulating film or the like interposed therebetween. The sub-guardelectrode SGE is disposed between the signal line S1 and the first glasssubstrate SUB1, and is formed of the same conductive material, such as ametal, as that of the control line C1. A first insulating film 11 isformed above the control line C1 and the sub-guard electrode SGE. Afirst semiconductor layer SC1 is formed on the first insulating film 11.The first semiconductor layer SC1 includes two channel regions facingthe control lines C1. The first semiconductor layer SC1 is located on aside of the first counter electrode CE1 opposite to the sensorelectrodes SE. The first semiconductor layer SC1 is formed of, forexample, polycrystalline silicon. The semiconductor layer SC1 may beformed of oxide semiconductors or amorphous silicon. A second insulatingfilm 12 is formed on the first insulating film 11 and the firstsemiconductor layer SC1.

The signal line S1, a first conductive layer CL1, and a first auxiliarywiring line A1 are formed on the second insulating film 12. The signalline S1, the first conductive layer CL1, and the first auxiliary wiringline A1 are located on the side of the first counter electrode CE1opposite to the sensor electrodes SE. The signal line S1, the firstconductive layer CL1, and the first auxiliary wiring line A1 are formedof the same conductive material, such as a metal.

The first auxiliary wiring line A1 is a wiring line for supplying theactive guard potential to the first counter electrode CE1 through acontact hole CHa1.

The signal line S1 is coupled to one end of the first semiconductorlayer SC1 through the contact hole CHa1 formed in the second insulatingfilm 12.

Since the sub-guard electrode SGE is provided between the signal line S1and the first glass substrate SUB1, it is possible to prevent noise frompassing from the lower side of the first glass substrate SUB1 (from asurface thereof opposite to the surface above which the sensorelectrodes SE are formed) to the signal line S1.

The signal lines S1 may be first formed above the first glass substrateSUB1, and the control lines C1 may be formed above the signal lines S1.In that case, the sub-guard electrode SGE is formed between the controllines C1 and the first glass substrate SUB1. The sub-guard electrode SGEmay be formed in the same layer as that of the signal lines S1, or maybe formed of the same material as that of the signal lines S1.

The active guard potential can be supplied to the sub-guard electrodeSGE through the first auxiliary wiring line A1. Although the activeguard potential is not limited to a particular range, supplying theactive guard potential in synchronization with the drive signal of thesensor electrodes SE can further reduce the parasitic capacitancesbetween the signal lines S1 and the sensor electrodes SE, and betweenthe control lines C1 and the sensor electrodes SE. If, in addition tothe first counter electrode CE1, such an auxiliary shield electrode isfurther provided at a location closer to the first glass substrate SUB1,a higher reduction effect of the parasitic capacitances can be obtained.

The first conductive layer CL1 is coupled between the channel regions ofthe first semiconductor layer SC1 through the contact hole formed in thesecond insulating film 12. The first auxiliary wiring line A1 is coupledto the other end of the first semiconductor layer SC1 through thecontact hole formed in the second insulating film 12.

A third insulating film 13 is formed above the second insulating film12, the signal line S1, the first conductive layer CL1, and the firstauxiliary wiring line A1. The third insulating film 13 has a contacthole that faces the first conductive layer CL1 and is open to the firstconductive layer CL1. The third insulating film 13 is a layercorresponding to the planarizing film PLN of FIG. 3 , and is preferablyformed of an organic material.

The first counter electrode CE1 is formed on the third insulating film13. The first counter electrode CE1 is coupled to the first auxiliarywiring line A1 through the contact hole CHa1 formed in the thirdinsulating film 13.

The counter electrode CE1 has a first opening OP1 that faces a firstdetection switch DS1 and that surrounds the contact hole of the thirdinsulating film 13. The counter electrode CE1 has not only the firstopening OP1, but also a plurality of openings, such as a second openingfacing a second detection switch, a third opening facing a thirddetection switch, and a fourth opening facing a fourth detection switch.

A fourth insulating film 14 is formed above the first conductive layerCL1, the third insulating film 13, and the counter electrode CE1. Thefourth insulating film 14 has a contact hole that faces the firstconductive layer CL1 and is open to the first conductive layer CL1. Eachof the sensor electrodes SE is formed on the fourth insulating film 14,and faces the first opening OP1. The sensor electrode SE is coupled tothe first conductive layer CL1 through the first opening OP1 and thecontact hole of the fourth insulating film 14.

The first detection switch DS1 including the first conductive layer CL1,the first semiconductor layer SC1, and a first switching element DS1 ais a specific example of the switching element according to the presentinvention.

The first switching element DS1 a includes a first electrodeelectrically coupled to the control line C1, a second electrodeelectrically coupled to the signal line S1, and a third electrodeelectrically coupled to the sensor electrode SE. The first electrodeserves as a gate electrode of a thin-film transistor (TFT); one of thesecond and third electrodes serves as a source electrode thereof; andthe other of the second and third electrodes serves as a drain electrodethereof. When the selection signal is supplied from a first control lineC1 to the sensor electrode SE, the first switching element DS1 a isturned on to supply the drive signal from a first signal line S1 to thesensor electrode SE, and the detection signal is supplied to the firstsignal line S1.

The fingerprint sensor operates when at least the first switchingelement DS1 a is provided as a switching element for driving thefingerprint sensor. In the present embodiment, however, a secondswitching element DS1 b is additionally provided to apply the activeguard potential to an unselected sensor electrode SE. The secondswitching element DS1 b includes a first electrode electrically coupledto the first control line C1, a second electrode electrically coupled tothe first auxiliary wiring line A1, and a third electrode electricallycoupled to the sensor electrode SE. The first electrode serves as a gateelectrode of a thin-film transistor (TFT); one of the second and thirdelectrodes serves as a source electrode thereof; and the other of thesecond and third electrodes serves as a drain electrode thereof. Whenthe selection signal is supplied from the first control line C1 to thesensor electrode SE, the second switching element DS1 b is turned on tosupply the active guard potential from the first auxiliary wiring lineA1 to the sensor electrode SE.

When the first detection switch DS1 includes the first switching elementDS1 a and the second switching element DS1 b coupled in series in thismanner, turning on one of the switching elements turns off the otherthereof. The first and the second switching elements DS1 a and DS1 b areformed of, for example, thin-film transistors of conductive typesdifferent from each other, such as an n-channel thin-film transistor anda p-channel thin-film transistor.

The first and the second switching elements DS1 a and DS1 b may haveeither a top-gate structure or a bottom-gate structure. Thesemiconductor layers of the first and the second switching elements DS1a and DS1 b are formed of polycrystalline silicon (poly-Si), but are notlimited to the polycrystalline silicon, and may be formed of, forexample, amorphous silicon or oxide semiconductors.

The coupling relations between the signal line S1 and the detectionswitch DS1 and between the auxiliary wiring line A1 and the detectionswitch DS1 are not limited to those of the example described above. Thesecond electrode of the first switching element in each detection switchDS1 may be coupled to the first auxiliary wiring line A1, and the secondelectrode of the second switching element in each detection switch DS1may be coupled to the signal line S1.

1-3. Bonded Structure

FIG. 5 is an exemplary schematic sectional view of a bonded structure ofthe fingerprint sensor according to the embodiment. The first and thesecond glass substrates SUB1 and SUB2 are bonded together by a sealingmaterial SL in a region overlapping the frame region PA. When the firstand the second glass substrates SUB1 and SUB2 are bonded together in theframe region PA, the gap formed between the glass substrates in thedetection region AA or the like is filled with the liquid crystals ofthe liquid crystal layer LQ. More specifically, a firston-glass-substrate circuit 4 is formed on the first glass substrateSUB1. The insulating film 2, the sensor electrode SE, and the alignmentfilm AL1 are sequentially stacked on the first on-glass-substratecircuit 4. The overcoat layer OC, the spacer SP, and the alignment filmAL2 are sequentially stacked on the second glass substrate SUB2. Thefirst and the second glass substrates SUB1 and SUB2 with these filmsformed thereon are bonded together by the sealing material SL disposedin the frame region PA.

After the glass substrates are bonded together, the liquid crystal layerLQ is filled with the liquid crystals by injecting the liquid crystalsfrom a filling opening provided in advance in the sealing material SL,and then the filling opening is sealed.

A one-drop-fill (ODF) process may be employed in which the liquidcrystals are dropped on the first glass substrate SUB1 or the secondglass substrate SUB2, and after the sealing material is printed in thesurrounding region of the liquid crystals, the glass substrates arelaminated together, and the sealing material is hardened.

FIG. 6 illustrates a modification of the bonded structure of thefingerprint sensor according to the embodiment. In this modification,the gap between the first and the second glass substrates SUB1 and SUB2is filled with the sealing material SL. In the present embodiment, thesealing material SL is disposed so as to overlap the entire surface ofthe frame region PA and the detection region AA, i.e., so as to overlapat least the entire surface of the second glass substrate SUB2, andbonds the first and the second glass substrates SUB1 and SUB2 together.

In this case, after an amount of the sealing material SL sufficient tospread over the entire surface of the first glass substrate SUB1 or thesecond glass substrate SUB2 is applied or printed thereon, the glasssubstrates are laminated together, and a hardening process, such asheating, is performed to bond the glass substrates together.

For example, a thermoset epoxy resin for an adhesive can be used as thesealing material SL. The use of such a sealing material can bond the twoglass substrates together such that the gap therebetween is uniform overthe entire region. The use of such a sealing material can bond the glasssubstrates together without a gap, i.e., seal the glass substrates. InFIG. 6 , the alignment films AL are formed for the first and the secondglass substrates SUB1 and SUB2. However, the alignment films AL need notbe provided in the present modification.

FIG. 7 illustrates a modification of the bonded structure of FIG. 6 .When the first and the second glass substrates SUB1 and SUB2 are bondedtogether by disposing the sealing material SL so as to overlap theentire surfaces of the substrates, the spacer SP need not be disposed.

When the spacer SP is disposed, an effect can be obtained that the gapbetween the first and the second glass substrates SUB1 and SUB2 isfurther uniformed over the entire region.

When the spacer SP is not disposed, air bubbles can be less likely to begenerated when the gap between the first and the second glass substratesSUB1 and SUB2 is filled with the sealing material.

1-4. Detection Principle

FIG. 8 illustrates an example of a detection principle of thefingerprint sensor according to the present embodiment. FIG. 8 is acircuit diagram illustrating a detector DT for the sensor electrode SE.In the present embodiment, the detector DT is coupled to the sensorelectrode SE through a connection wiring line W1. The connection wiringline W1 and the sensor electrode SE may be coupled together through thesignal line drive circuit MU (not illustrated). The number of thedetectors DT is, for example, the same as the number of the connectionwiring lines W1. In this case, the detectors DT are coupled to theconnection wiring lines W1 on a one-to-one basis.

As illustrated in FIG. 8 , the detector DT includes an integrator IN, areset switch RST, a switch SW1, and a switch SW2. The integrator INincludes an operational amplifier AMP and a capacitor CON. In thisexample, the capacitor CON is coupled between the non-inverting inputterminal and the output terminal of the operational amplifier AMP. Thereset switch RST is coupled in parallel with the capacitor CON. Theswitch SW1 is coupled between a signal source SG and the connectionwiring line W1. The switch SW1 switches between applying and notapplying a sensor drive signal Vw from the signal source SG to thesensor electrode SE through the connection wiring line W1 and the like.The switch SW2 is coupled between the connection wiring line W1 and thenon-inverting input terminal of the operational amplifier AMP. Theswitch SW2 switches between supplying and not supplying a detectionsignal Vr to the non-inverting input terminal described above.

When the detector DT described above is used, first, the switch SW1 isturned on, and the switch SW2 is turned off to write the sensor drivesignal Vw to the sensor electrode SE through the connection wiring lineW1 and the like. Subsequently, the switch SW1 is turned off, and thenthe switch SW2 is turned on to supply the detection signal Vr extractedfrom the sensor electrode SE through the connection wiring line W1 andthe like to the non-inverting input terminal described above. Theintegrator IN integrates the supplied voltage (detection signal Vr) overtime. Through this processing, the integrator IN can output a voltageproportional to the supplied voltage as an output signal Vout. Then, thereset switch RST is turned off to discharge a charge of the capacitorCON and thus to reset the value of the output signal Vout.

The detection principle of the present embodiment has been described byway of an example of a self-capacitance method in which the sensor drivesignal Vw is written to the sensor electrode SE through the connectionwiring line W1, and the detection signal Vr is read. However, thedetection principle is not limited to this example.

1-5. Structure of Second Counter Electrode

FIG. 9 is an exemplary schematic sectional view of a fingerprint sensorthat includes a second counter electrode. A second counter electrode CE2facing the sensor electrodes SE is formed on a first surface 7 of thesecond glass substrate SUB2, i.e., on a surface of the second glasssubstrate SUB2 closer to the first glass substrate SUB1. The secondcounter electrode CE2 serves as a guard electrode, and is preferablysupplied with the active guard potential described above. Disposing theglass substrate above the sensor electrodes SE increases the distancebetween the sensor electrodes SE and the finger, and thus lowers thedetection sensitivity of the sensor electrodes SE. However, the secondcounter electrode CE2 is disposed on the substrate which the fingercomes into proximity to or contact with, i.e., on the second glasssubstrate SUB2, and is supplied with a potential having the same phaseand amplitude as those of the drive signal, which is similar to theactive guard potential. As a result, an effect is obtained that anelectric field of the drive signal generated from the sensor electrodesSE is amplified above the second glass substrate SUB2, and thus thedetection sensitivity of the fingerprint sensor is improved.

Interposing the glass substrate increases a distance between the sensorelectrodes SE and the finger, and differentiates a distance between thesensor electrode SE and a dented portion of an uneven surface of thefingerprint on the second glass substrate SUB2 from a distance betweenthe sensor electrode SE and a projected portion of the uneven surfacethereof. Consequently, the fingerprint data obtained when the detectionsignal is calculated may blur. However, by disposing the second counterelectrode CE2 described above and supplying thereto the potential havingthe same phase and amplitude as those of the drive signal, which issimilar to the active guard potential, the signal intensity of thesensor can be increased, and thereby the blur of the data can bereduced. The potential supplied to the second counter electrode CE2 ispreferably the same potential as that of the drive signal.

The second counter electrode CE2 is formed of ITO, but is not limitedthereto, and may be formed of a metal film. The second counter electrodeCE2 is coupled to a sensor circuit connection wiring line 5 through aconductive path 6. The conductive path 6 is formed of, for example,silver paste or conductive tape. The sensor circuit 3 is formed on thefirst glass substrate SUB1, and is coupled to the sensor circuitconnection wiring line 5. The second counter electrode CE2 is suppliedwith the drive signal from the sensor circuit 3 through the sensorcircuit connection wiring line 5. The drive signal is, however, notlimited to being supplied through such a conductive path. For example, adrive signal supply circuit may be formed on the second glass substrateSUB2.

FIG. 10 illustrates a modification of the fingerprint sensor of FIG. 9 .In this modification, the second counter electrode CE2 opposed to thesensor electrodes SE is formed on a second surface 8 of the second glasssubstrate SUB2, i.e., on a surface of the second glass substrate SUB2opposite to the first glass substrate. The second counter electrode CE2thus formed on the second surface 8 of the second glass substrate SUB2can amplify the electric field of the drive signal at a location closerto the finger, and thereby provides a higher effect of improving thedetection sensitivity and the accuracy of the fingerprint sensor.

FIG. 11 is a plan view of the second counter electrode CE2. The secondcounter electrode CE2 is formed to have a pattern that overlaps thesecond glass substrate SUB2 thereabove in the plan view, and thatsurrounds peripheries of the respective sensor electrodes SE so as notto overlap the sensor electrodes SE. The second counter electrode CE2 isalso disposed on the frame region PA surrounding the detection regionAA. The width of the second counter electrode CE2 is larger in the frameregion PA than in the detection region AA. Such a pattern shape enablesamplification of the drive signal generated from the sensor electrodesSE without shielding the drive signal. However, the pattern shape of thesecond counter electrode 2 is not limited to this pattern shape.

The sensor circuit connection wiring line 5 is coupled to a connector 9,and coupled to the sensor circuit 3 through the connector 9. The methodfor driving the second counter electrode CE2 is not limited to thismethod. The second counter electrode CE2 may be driven by a drivecircuit, such as a flexible substrate, through the connector 9.

1-6. Sensor Drive Electrode on Second Glass Substrate

FIG. 12 is an exemplary sectional view of a sensor drive electrode SDEdisposed on the second glass substrate SUB2. In FIG. 12 , the sensordrive electrode SDE is formed on the first surface 7 of the second glasssubstrate SUB2 (on a surface thereof closer to the first glass substrateSUB1).

The sensor drive electrode SDE is coupled to the sensor circuitconnection wiring line 5 through the conductive path 6. The sensor driveelectrode SDE can be supplied with the drive signal from the sensorcircuit 3 through the sensor circuit connection wiring line 5. However,the drive signal is not limited to being supplied in this manner. Adrive signal supplying power source may be disposed on the second glasssubstrate.

The drive signal is transmitted from the sensor drive electrode SDE, andthe sensor electrode SE receives the drive signal as a received signalthrough the finger. The fingerprint in proximity to or contact with thefingerprint sensor can be recognized based on the received signal. Thatis, the sensor electrode SE serves as a detection electrode in thiscase.

FIG. 13 illustrates a modification of the sensor drive electrode of FIG.12 . In FIG. 13 , the sensor drive electrode SDE is formed on the secondsurface 8 of the second glass substrate SUB2. This modification improvesthe detection sensitivity of the fingerprint sensor because the sensordrive electrode SDE is closer to the finger.

FIG. 14 is a plan view of the sensor drive electrode SDE on the secondglass substrate. The sensor drive electrode SDE is formed in the frameregion PA of the fingerprint sensor 1 so as to surround the detectionregion AA. The sensor drive electrode SDE can be formed of ITO, IZO,ZnO, or a metal film, for example.

FIG. 15 illustrates an example of a detection principle of the presentembodiment. An RF method is an example of a method for detecting thefingerprint by using the sensor drive electrode SDE as a drive electrodeand the sensor electrode SE as a detection electrode. In the capacitancemethod described above, the fingerprint is detected based on thedifference in capacitance change caused by the unevenness of the surfaceof the finger F. In the RF method, a high-frequency drive signal istransmitted to the conductive dermis lying under the epidermis of thefinger, and an electric field generated by dermal cells is detected as adetection signal. In FIG. 15 , the drive electrode SDE transmits thehigh-frequency sensor drive signal Vw. A change caused by the electricfield indicating information on the microstructure of the dermal cellsof the finger F is added to the sensor drive signal Vw to obtain thedetection signal Vr, and the detection electrode (sensor electrode SE inthis example) receives the detection signal Vr. However, the principlefor detecting the microstructure, such as that of the fingerprint, byusing the sensor drive electrode SDE and the sensor electrodes SE is notlimited to the above example.

1-7. Method for Driving Fingerprint Sensor

FIG. 16 is an exemplary circuit diagram for illustrating a method fordriving the fingerprint sensor according to the present embodiment. InFIG. 16 , under the control of a controller CU (not illustrated), thecontrol line drive circuit CD simultaneously supplies a drive signal CSat an on level (power supply voltage Vdd) to a first control line C1 anda second control line C2, and supplies the drive signal CS at an offlevel (power supply voltage Vss) to control lines C3 and C4 other thanthe first and the second control lines C1 and C2.

The on-level drive signal CS (power supply voltage Vdd) is a selectionsignal for the control lines C, and the off-level drive signal CS (powersupply voltage Vss) is a non-selection signal for the control lines C.As a result, the detection switches DS in the first and the second rowsare brought into a conduction state. In the signal line drive circuitMU, a second control switch CSW2 and a third control switch CSW3 arebrought into the conduction state, and a first control switch CSW1 and afourth control switch CSW4 are brought into a non-conduction state. Asixth control switch CSW6 is also brought into the non-conduction state.

As a result, four adjacent sensor electrodes SE shaded with diagonallines among the sensor electrodes SE in the first and the second rowsare electrically bundled, and brought into a selected state. The sensordrive signal Vw is supplied to a second signal line S2, a third signalline S3, a sixth signal line S6, and a seventh signal line S7 amongfirst to eighth signal lines S1 to S8. As a result, it is possible tocollectively perform writing of the sensor drive signal Vw and readingof the detection signal Vr to and from the four bundled sensor driveelectrodes SE through one connection wiring line W1.

In a subsequent sensing period, the signal line drive circuit MU, forexample, brings the second and the third control switches CSW2 and CSW3into the conduction state, and brings the first, the fourth, and thesixth control switches CSW1, CSW4 and CSW6 into the non-conductionstate, whereby the electric bundle of the four adjacent sensorelectrodes SE can be shifted rightward by one signal line. In thismanner, the operation of detection is repeated while shifting the sensorelectrodes SE at a predetermined pitch, and obtained output signals areadded to obtain a calculation result, whereby high-resolutionfingerprint data with less blur can be obtained.

Ends of the connection wiring lines W1 are coupled to the controller CU(not illustrated). The controller CU controls various control signalsand the selection signal, and may include, for example, a circuit fordetecting the detection signal, a circuit for calculating the outputresult, a power source for supplying the drive signal, and an analogfront-end (AFE) that performs digitalization of the detection signal orthe like.

FIG. 17 illustrates the method for driving the self-capacitancefingerprint sensor that includes the first and the second counterelectrodes. In FIG. 17 , the sensor electrodes SE are coupled torespective switching elements DS1 a to DS6 a that are coupled to thesignal line S1 or S2, and to respective switching elements DS1 b to DS6b that are coupled to an auxiliary wiring line A1 or A2. The controlline drive circuit CD supplies the on-level drive signal CS (powersupply voltage Vdd) or the off-level drive signal CS (power supplyvoltage Vss) to the control lines C. In the circuit of FIG. 17 , thecontrol line drive circuit CD selects one control line C to be driven bysequentially supplying the on-level drive signal CS (power supplyvoltage Vdd) to the control lines C row by row, and supplies theoff-level drive signal CS (power supply voltage Vss) to unselectedcontrol lines C. Each of the control lines C is coupled to switchingelements that are coupled to the respective sensor electrodes SEbelonging to one row. The switching elements DS3 a and DS4 aelectrically connect the respective sensor electrodes SE to the signalline S1 or S2, and the switching elements DS3 b and DS4 b electricallydisconnect the respective sensor electrodes SE from the auxiliary wiringline A1 or A2. The switching elements DS3 a and DS4 a and the switchingelements DS3 b and DS4 b are coupled to the control line C supplied withthe on-level drive signal CS (power supply voltage Vdd). The switchingelements DS1 a, DS2 a, DS5 a, and DS6 a electrically disconnect therespective sensor electrodes SE from the signal line S1 or S2, and theswitching elements DS1 b, DS2 b, DS5 b, and DS6 b electrically connectthe respective sensor electrodes SE to the auxiliary wiring line A1 orA2. The switching elements DS1 a, DS2 a, DS5 a, and DS6 a and theswitching elements DS1 b, DS2 b, DS5 b, and DS6 b are coupled to therespective control lines C supplied with the off-level drive signal CS(power supply voltage Vss).

In FIG. 17 , the signal lines S are supplied with the sensor drivesignal Vw through the signal line drive circuit MU, and the auxiliarywiring line A is supplied with an active guard potential Va from thecontroller CU through the signal line drive circuit MU. That is, thesensor electrodes SE belonging to the control line C supplied with theon-level drive signal CS (power supply voltage Vdd) are supplied withthe sensor drive signal Vw through the signal line drive circuit MU, andoutput the detection signal Vr. The sensor electrodes SE belonging tothe control lines C supplied with the off-level drive signal CS (powersupply voltage Vss) are supplied with the active guard potential Vathrough the signal line drive circuit MU.

In the timing diagram on the right side of FIG. 17 , the on-level drivesignal CS (power supply voltage Vdd) is supplied to the control linesCn, Cn+1, and Cn+2 at different timing, so that the row of the sensorelectrodes SE selected to be driven is shifted one by one. The left-handdiagram of FIG. 17 illustrates the connection state (connection state attiming enclosed by dotted line in the right-hand diagram) when thecontrol line Cn+1 is selected. The control line Cn+1 is supplied withthe on-level drive signal CS (power supply voltage Vdd), and a groupSEn+1 of two adjacent sensor electrodes SE is selected. As a result, thesensor electrodes SEn+1 are supplied with the sensor drive signal Vwfrom the controller CU through the signal line drive circuit MU, andsensor electrodes SEn and sensor electrodes SEn+2 are supplied with theguard signal Va. The first counter electrode CE1 (not illustrated inFIG. 17 ) is disposed so as to face the sensor electrodes SE and overlapthe entire surface of the detection region AA. The second counterelectrode CE2 is disposed along outer peripheries of the sensorelectrodes SE so as to overlap a part of the detection region AA and theframe region PA that do not overlap the sensor electrodes SE. The firstcounter electrode CE1 and the second counter electrode CE2 are suppliedwith the active guard potential Va that has the same phase and amplitudeas those of the sensor drive signal Vw during the entire detectionperiod of the fingerprint sensor for any of the control lines C, insynchronization with the sensor drive signal Vw.

FIG. 18 illustrates the RF method for driving the fingerprint sensorthat includes the sensor drive electrode. In FIG. 18 , the sensorelectrodes SE are coupled to the respective switching elements DS1 a toDS6 a that are coupled to the signal line S1 or S2.

Each of the switching elements DS1 a to DS6 a includes an n-typethin-film transistor. The control line drive circuit CD supplies theon-level drive signal CS (power supply voltage Vdd) or the off-leveldrive signal CS (power supply voltage Vss) to the control lines C. Inthe circuit of FIG. 18 , the control line drive circuit CD selects onecontrol line C to be driven by sequentially supplying the on-level drivesignal CS (power supply voltage Vdd) to the control lines C row by row,and supplies the off-level drive signal CS (power supply voltage Vss) tounselected control lines.

Each of the control lines C is coupled to switching elements that arecoupled to the respective sensor electrodes SE belonging to one row. Theswitching elements DS3 a and DS4 a coupled to the control line Csupplied with the on-level drive signal CS (power supply voltage Vdd)electrically connect the respective sensor electrodes SE to the signalline S1 or S2, and the switching elements DS1 a, DS2 a, DS5 a, and DS6 acoupled to the control lines C supplied with the off-level drive signalCS (power supply voltage Vss) electrically disconnect the respectivesensor electrodes SE from the signal line S1 or S2. The sensor electrodeSE outputs the detection signal Vr to the signal line drive circuit MUand the controller CU through the signal lines S.

In the timing diagram on the right side of FIG. 18 , the on-level drivesignal CS (power supply voltage Vdd) is supplied to the control linesCn, Cn+1, and Cn+2 at different timing, so that the row of the sensorelectrodes SE selected to be detected is shifted one by one. Theleft-hand diagram of FIG. 18 illustrates the connection state(connection state at timing enclosed by dotted line in the right-handdiagram) when the control line Cn+1 is selected. The control line Cn+1is supplied with the on-level drive signal CS (power supply voltageVdd), and the group SEn+1 of two adjacent sensor electrodes SE isselected. As a result, the detection signal Vr is output from the sensorelectrodes SEn+1 to the controller CU through the signal line drivecircuit MU.

In FIG. 18 , the sensor drive electrode SDE is disposed along the frameregion PA. The sensor drive electrode SDE is supplied with the sensordrive signal Vw during the entire detection period of the fingerprintsensor for any of the control lines C.

The sensor electrode SE belonging to the selected control line receivesan electromagnetic wave supplied from the sensor drive electrode SDEthrough the finger, and outputs the detection signal Vr to the signallines S. The controller CU includes the detector DT (not illustrated),and detects the detection signal Vr from the sensor electrode SE.

In FIG. 18 , the sensor electrodes SE belonging to the rows of theunselected control lines (control lines supplied with the off-leveldrive signal CS) are not coupled to the signal lines S, i.e., notcoupled to the detection circuit, and are consequently set at thefloating potential.

1-8. Method for Manufacturing Fingerprint Sensor

In the fingerprint sensor according to the present embodiment, the twoglass substrates interpose the sensor electrodes SE therebetween, andare bonded together without a gap, i.e., sealed by the sealing material.Thereafter, the glass substrates are wet-etched to be subjected todissolution, and thus can be reduced in film thickness. That is, the twoglass substrates are sealed by the sealing material, and then areimmersed in an etching solution to be adjusted to have a desired filmthickness. The two glass substrates are preferably adjusted to each havea film thickness in the range of 100 μm to 300 μm. The liquid crystalscan be injected between the two glass substrates before the etchingprocess. Then, the glass substrates are cut as needed. Employing thismethod makes it possible to manufacture a thinner fingerprint sensorwith higher detection sensitivity, and also a smaller and lighterfingerprint sensor. A known polishing method or etching method can beused as the method for adjusting the film thickness of the glasssubstrates. Using the wet etching method is preferable because it makesthe glass hard to be cracked.

1-9. Fingerprint Sensor Module

FIG. 19 is an exemplary schematic plan view of a fingerprint sensormodule 15 according to the present embodiment. FIG. 20 is an exemplaryschematic side view of the fingerprint sensor module 15 according to thepresent embodiment. The fingerprint sensor module 15 includes a flexiblesubstrate 10 coupled onto the first glass substrate SUB1 included in thefingerprint sensor 1 and the controller CU disposed on the flexiblesubstrate 10. The controller CU is a component that can transmit andreceive signals and data between external equipment and the fingerprintsensor. The controller CU includes, for example, the detector DT thatreceives the detection signal Vr output from the signal lines S throughthe signal line drive circuit MU. The controller CU may include ananalog front-end (AFE) that performs data conversion on the detectionsignal Vr.

The controller CU may be disposed on the first glass substrate SUB1. Thesignal line drive circuit MU and the control line drive circuit CD maybe included in the controller CU disposed on the flexible substrate 10,instead of being disposed on the first glass substrate. The signal linesS coupled to the respective sensor electrodes SE are coupled from thesignal line drive circuit MU to the controller CU through the connectionwiring line W1 (not illustrated).

When the fingerprint sensor module 15 is built into an electronicapparatus, such as a personal computer, a mobile phone, a tablet, and acard with a biometric authentication function, through the controller CUdisposed on the flexible substrate 10, the fingerprint sensor module 15can exchange any selection signal, any control signal, and anysynchronization signal between the controller CU and an operating system(OS) or an application processor of the electronic apparatus so as toallow the OS to easily control the fingerprint sensor. The detectiondata detected by the detector DT is transmitted through the controllerCU to, for example, the application processor of the electronicapparatus so as to perform image conversion from the detection data intocertain fingerprint data, perform data correction processing, andperform association with any system or software for authentication in aneasy way. The controller CU may perform synchronization among modules orprocessing of the detection data by transmitting and receiving signals,for example, to and from a display circuit control driver of a displaydevice incorporating the fingerprint sensor module 15, or to and from atouch detection driver of a touchscreen (touchscreen larger than thefingerprint sensor) incorporating the fingerprint sensor 1. Thefingerprint sensor module 15 that is reduced in thickness and size andincreased in durability in this manner can be easily incorporated in anyelectronic apparatus, and achieves lower manufacturing cost and higherversatility than in the case of directly integrating the fingerprintsensor into the electronic apparatus.

1-10. Decorative Layer

The fingerprint sensor according to the present invention may alsoinclude a decorative layer.

FIG. 21 illustrates an exemplary sectional view of the decorative layeraccording to the present embodiment. In FIG. 21 , a decorative layer 16is disposed between the second glass substrate SUB2 and the overcoatlayer OC so as to overlap the entire surface of the second glasssubstrate SUB2. The decorative layer may also serve as the overcoatlayer.

The decorative layer 16 may be disposed so as to overlap only the frameregion PA, as illustrated in FIG. 22 . Any colored layer can be used asthe decorative layer 16. The decorative layer 16 may be a black matrixlayer.

FIG. 23 illustrates a plan view of a dummy electrode DE formed in theframe region PA. The dummy electrode DE may be formed as the same layeras the sensor electrodes SE. The dummy electrode DE may be formed so asto overlap the decorative layer 16 disposed in the frame region PA. Thedummy electrode may be supplied with the active guard potential.

1-11. Other Functions

The fingerprint sensor according to the present invention can be usednot only as a sensor for the fingerprint detection, but also as a smallthin sensor for detecting biological microstructures.

What is claimed is:
 1. A fingerprint sensor comprising: a substrate; aplurality of sensor electrodes arranged on the substrate; a plurality offirst switches coupled to the sensor electrodes; an organic layercovering the sensor electrodes; a control line drive circuit that isprovided and long in a first direction; a signal line drive circuit thatis provided and long in a second direction orthogonal to the firstdirection; a plurality of signal lines coupled to the first switches; aplurality of control lines coupling the first switches to the controlline drive circuit; a sensor drive electrode surrounding the sensorelectrodes; a plurality of second switches that are provided between thesignal line drive circuit and the signal lines and in a one-to-onecorrespondence with the signal lines; and a first number of thirdswitches that are provided between the signal line drive circuit and thefirst number of second switches of all the second switches and in aone-to-one correspondence with the first number of second switches,wherein a position of a surface of the organic layer is lower than aposition of the sensor drive electrode, and wherein the first number isless than the number of all the second switches.
 2. The fingerprintsensor according to claim 1, wherein the second switches and the thirdswitches are configured to be individually switched between a conductionstate and a non-conduction state, and wherein a distance of the sensordrive electrode from a surface of the substrate is larger than adistance of the sensor electrodes from the surface of the substrate. 3.The fingerprint sensor according to claim 2, further comprising: acounter electrode covering the signal lines and the control lines,wherein the counter electrode overlaps the sensor electrodes.
 4. Thefingerprint sensor according to claim 3, wherein the sensor electrodesare made of transparent electrodes.
 5. The fingerprint sensor accordingto claim 4, wherein the counter electrode is made of a transparentelectrode.